There have been a number of proposals to automate retail price displays by the use of electronic price tags. To the extent such systems replace printed price tags, these systems are appealing to store owners because they reduce or eliminate the need to reprint and replace item price tags each time the price of an item is changed. This benefits the retailer by reducing or eliminating: the labor required to replace the price tags; the possibility of human error in replacing the price tags; the time lag involved in changing prices; and the difficulty in changing a large number of prices at once. Perhaps most importantly, such systems have the ability to overcome price discrepancies between the tag and the checkout scanners.
Problems have been encountered, however, in providing the requisite information and power to the electronic tags at a reasonable cost. Also, some systems still require printed product description labels on the tags to supplement the electronic tags and thus do not eliminate the problems they were intended to solve. In systems in which the electronic tags are hard wired, installation and removal of the electronic tags is expensive and impractical. Systems which use exposed wires and connectors are undesirable because they reduce the system's reliability and subject the system to damage from electrostatic discharges, spillage and surface oxides. Other systems lack the ability to verify the accuracy of the displays and the proper functioning of the electronic tags while the system is in operation.
A number of wireless display systems have been proposed which rely on infrared, acoustic, or radio frequency broadcast for transmission of product information to the display tags. These wireless tags require a battery for powering each tag. Adding a battery to the tag increases the cost of each tag and can make the overall system unaffordable for many applications. Moreover, since a single retail establishment often contains as many as 20,000 to 50,000 display tags, replacement of the batteries and reprogramming such a large number of tags is time-consuming and costly. The radiated signals can also be shielded, for example, by steel freezer cases, causing communication "dead spots" in a store. Moreover, disposing of batteries has an adverse environmental impact. If there are just 50,000 installations with 20,000 tags each, that is a billion batteries that have to be disposed of on a routine basis, and the labor involved in replacing the batteries and reprogramming at each battery change is costly as well. Effective use of such systems requires a battery management system so that the batteries can be replaced before failure, or before the quality of the tag's display diminishes to an unacceptable level. Further, because the tags in a wireless system generally do not communicate problems to the computer, the tags have to be visually monitored to identify problems such as bad or faint tags.
Another problem in most previously proposed electronic display tag systems is that the tags have been relatively thick, causing them to protrude from the shelf rails on which they are mounted. Protruding tags are subject to damage by shopping carts, and they can impede the movement of store customers within the aisles. Further the protrusion of the tags into the aisle invites tampering and can result in theft of the electronic tags.